1. Technical Field
The present disclosure relates to a switch mechanism for a pneumatic tool. More particularly, the present disclosure relates to a switch mechanism for a pneumatic tool favoring both right-handed users and left-handed users to operate with only one hand.
2. Description of Related Art
A pneumatic tool is a tool driven by pressurized air for screwing or drilling, such as a pneumatic drill or a pneumatic wrench. A forward air channel, a reverse air channel and a reversible valve are disposed inside the pneumatic tool. When the pneumatic tool is in a forward operation mode in which a fastener is tightened, a gas port of the reversible valve is communicated with the forward air channel, so that the pressurized air can flow into the forward air channel for driving the pneumatic tool to rotate in a forward direction. In similar fashion, when the pneumatic tool is in a reverse operation mode, the gas port of the reversible valve is communicated with the reverse air channel, so that the pressurized gas can flow into the reverse air channel for driving the pneumatic tool to rotate in a reverse direction. The pneumatic tool is typically provided with a switch mechanism for switching an operation mode of the pneumatic tool between the forward operation mode and the reverse operation mode.
A conventional switch mechanism usually includes a lever which unilaterally protrudes from a predetermined side of the pneumatic tool. Due to the right-handed users are far more than the left-handed users, the side of the pneumatic tool where the lever protrudes from is mostly designed for the right-handed users. When a right-handed user holds the pneumatic tool with a right hand, the right-handed user can toggle the protruding portion of the lever up or down with a right thumb for driving the reversible valve to rotate so as to control the gas port of the reversible valve to communicate with the forward air channel or the reverse air channel. In other words, the right-handed user can operate the pneumatic tool with only one hand.
However, when a left-handed user holds the aforementioned pneumatic tool with a left hand, the left-handed user have to toggle the protruding portion of the lever up or down with a thumb of the other hand. During work, the other hand is usually occupied with other items such as bolts, nut, and the likes. Therefore, such pneumatic tool is unfavorable to the left-handed user.
For solving the foregoing problem, another kind of pneumatic tool with a lever bilaterally protruding from the pneumatic tool is disclosed. The lever of the pneumatic tool cannot be adjusted to unilaterally protrude from the pneumatic tool. Both the right-handed user and the left-handed user can hold the pneumatic tool and toggle the lever with only one hand. That means both the right-handed user and the left-handed user only use one of the two protruding portions of the lever, and the other protruding portion of the lever becomes a redundant burden. For example, when the user is working in a confined space, the user is further confined in the space due to the extra protruding portion of the lever. Moreover, an unexpected change of a rotation direction of the pneumatic tool may be caused by inadvertently hitting the extra protruding portion of the lever.
The protruding portion of the lever may be shortened in length to reduce the chance of inadvertent hits. However, when the length of the protruding portion of the lever is shortened, it inevitably becomes more difficult for the user to toggle the lever, because a greater force is needed for toggling the lever. Therefore, the aforementioned pneumatic tool is unfavorable to the users.